Description: A general instance of Theorem *2.521 of WhiteheadRussell p. 107. (Contributed by NM, 3-Jan-2005) (Proof shortened by Wolf Lammen, 8-Oct-2012)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | pm2.521g2 | |- ( -. ( ph -> ps ) -> ( ch -> ph ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | simplim | |- ( -. ( ph -> ps ) -> ph ) |
|
| 2 | 1 | a1d | |- ( -. ( ph -> ps ) -> ( ch -> ph ) ) |